(a) Technical Field
The present disclosure relates, generally, to a position sensorless detection method of a high performance permanent magnet synchronous motor during emergency operation. More particularly, it relates to a position sensorless control method of a high performance permanent magnet synchronous motor during emergency operation, which can accurately detect a magnetic pole position of the synchronous motor based on a position sensorless vector control using an adaptive observer that is configured based on a permanent magnet synchronous motor model.
(b) Background Art
An inverter for controlling a motor generally comprises a converter unit, an inverter unit, and a control unit. Generally, the converter unit, which is composed of a three-phase full-wave rectifier circuit and a smoothing circuit, smoothes an alternating current and outputs a current with a small ripple component. The inverter unit generates an alternating current having a predetermined frequency by switching the direct current converted by the converter unit by means of a semiconductor device such as a transistor. The controller, which is composed of an operation circuit, a detection circuit, a drive circuit, etc., controls the switching of the inverter and the voltage of the converter and performs various protection functions.
Control methods typically used in the inverter include a pulse width modulation (PWM) control method and a vector control method. The PWM control method is used to control the frequency and the output voltage (or current) by means the inverter unit, in which the semiconductor device is switched by high frequency to change the width of the switching pulse, thus controlling the voltage (or current).
The vector control method is used to suitably control the current of the motor by dividing it into excitation current and torque current, in which the slip of the motor is detected by a speed detector to suitably calculate the magnitude of load and a current suitable for the torque according to the magnitude of load is applied to the motor, thus ensuring a predetermined excitation current.
In order to control the motor according to a conventional method, first of all, it is necessary to suitably detect an initial magnetic pole position and determine a rotational speed and a magnetic pole position during control. Second, it is necessary to carry out vector control since a stable control is not available during voltage/frequency (V/F) control. And third, it is necessary to determine an initial angular position of a motor rotor to perform the vector control, it is necessary to divide the current of the motor into excitation current and torque current, and it is necessary to measure the speed and position of the motor rotor for this operation process.
Various sensorless control methods for the motor control have been proposed and include, for example, a method of using extended electromotive force (EEMF), a method of obtaining speed and position by estimating the magnetic flux using an observer, and the like.
However, there remains a need in the art for a sensorless detection method of a high performance permanent magnet synchronous motor during emergency operation.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.